I am currently creating a piece that requires 5 solenoids to be activated simultaneously by a proximity sensor.

I am now having difficulty with the external power. if each solenoid is 12v I will need a total of 60v then (less is okay)... to measure amperage I can just use a multi-meter? will it need to have a load when measuring?

SHOULD I combine all voltage and use a 60v power supply? or make my life easier and use multiple adapters? it is the amperage that is confusing me.

(first terminal is coming in from arduino pin 13, all share arduino GRND, and second terminal is where power supply will be)

actually DDRYA,though picture speak a thousand word, for the life of me i cant actually see what type of transistor ur using, whether the yellow wire on top is the positive or the negative side of the circuit. however about our question, usually when you are powering a project and want to switch on and of a solenoid it is always better that you make the connection parallel.So in that sense you could use a 12Vdc power supply but 14Vdc would be a better choice since there would be a drop in the transistor, however i would also warn you that the arduino have an absolute max Vdc input of 12Vdc.So my suggestion to you is that,if you are willing to use 2 power supply then,1 7Vdc power supply for your arduino and 1 14Vdc power supply for your solenoid.oruse a single 12Vdc power supply, is good for both.

You really need to try and draw out and post the circuitry in schematic form (with component values and part numbers) and also show how the solenoids wire up and how the arduino controls the transistors. Without that it's just a bunch of guesses of what may or may not be wrong with your wiring.

Seems unlikely, you'll need 12 or a little more as Ash remarked. What you need to worry about is how much current the supply can provide. Look at the documentation for your solenoids to find the maximum draw and that'll tell you the absolute minimum you need from a power supply. Some headroom and some allowance for the consumption of the other components would be sensible, but I'd expect the solenoids to be the lion's share of it.

Great I really appreciate the help. Just to clarify I will be powering arduino via its 5v power supply. So the additional 12v external supply will be enough for 5x12v solenoids? And I only need to concern myself with current?

Yes, but you will have to select a 12V power supply that can supply at least five times whatever current one solenoid draws and you would not want to be running the supply at its limit, so you will need some additional current capacity too.